Perfluororubber laminate and processes for producing the same

ABSTRACT

A laminate, which is in the form of an O-ring, a square ring, a rubber roll, a diaphragm, a rubber hose, a rubber tube or a vial stopper, comprising a layer of a perfluororubber, a layer of other rubber and an adhesive layer containing a polyfunctional compound which adheres the rubber layers by vulcanization is produced by coating a polyfunctional compound on a surface of at least one of the perfluororubber layer or the other rubber layer, laminating the layers with the coated surface facing the other layer, and vulcanizing the layers to adhere them. Thereby, the adhesion strength between the layer of perfluororubber and the layer of the other rubber is improved.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP98/04773 which has an Internationalfiling date of Oct. 22, 1998, which designated the United States ofAmerica.

FIELD OF THE INVENTION

The present invention relates to a laminate of a perfluororubber and amethod for producing the same. In particular, the present inventionrelates to a laminate comprising a layer of a perfluororubber and alayer of other rubber, which are adhered by vulcanizing, and a methodfor producing the same.

BACKGROUND ART

Perfluororubbers are used in various fields which require chemicalresistance, thermal properties (in particular, high temperatureproperties), etc., since they are excellent in such properties.

However, the perfluororubbers are generally expensive and have inferiormechanical properties (e.g. tensile strength, elongation at break, etc.)to general fluororubbers. Thus, it is preferable to use theperfluororubbers in the form of a laminate with other materials, but theperfluororubbers inherently have low adhesion properties with othermaterials. Furthermore, neither primers nor adhesives have beendeveloped to adhere the perfluororubbers to other materials in goodcondition.

JP-A-64-54037 proposes the addition of an adhesion aid to other rubberswhich are adhered to the perfluororubbers to improve the adhesionproperties between them. However, in the case of a laminate comprising alayer of other rubber and a layer of a perfluororubber surrounding thelayer of the other rubber, the adhesion aid compounded in the otherrubber cannot diffuse outside of the laminate in the course of thesecondary vulcanization. Rather, the adhesion aid accumulates at theinterface between the layer of the other rubber and the layer of theperfluororubber, and interferes with the adhesion between the layers.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a laminate comprisinga layer of a perfluororubber and a layer of other material, inparticular, other rubber, which are bonded with a high adhesionstrength, irrespective of the shape of the laminate.

Another object of the present invention is to provide a method forproducing such a laminate.

To achieve the above objects, the present invention provides a laminatecomprising a layer of perfluororubber, a layer of other rubber and anadhesive layer containing a polyfunctional compound which adheres bothrubber layers by vulcanization, and a method for producing a laminatecomprising the steps of coating a polyfunctional compound on a surfaceof at least one of a layer of a perfluororubber and a layer of otherrubber, laminating the layers with the coated surface facing the otherlayer, and vulcanizing the layers to adhere them.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of one example of an O-ring and a square ring,

FIG. 2 is a cross section of one example of an O-ring and a square ring,

FIG. 3 is a cross section of one example of an O-ring and a square ring,

FIG. 4 is a cross section of one example of an O-ring and a square ring,

FIG. 5 is a cross section of one example of an O-ring and a square ring,

FIG. 6 is a cross section of one example of an O-ring and a square ring,and

FIG. 7 is a cross section of one example of an O-ring and a square ring.

DETAILED DESCRIPTION OF THE INVENTION

The perfluororubber used in the present invention may be a knownperfluororubber. A preferable example of the perfluororubber is acopolymer of a perfluoroalkylene having 2 to 6 carbon atoms, preferably,tetrafluoroethylene, a perfluoroalkyl vinyl ether of the formula (I):

Rf—O—(CFXCF₂O)_(n)—CF═CF₂  (I)

wherein Rf is a perfluoroalkyl group having 1 to 5 carbon atoms, X is afluorine atom or a trifluoromethyl group, and n is an integer of 0 to 4,and a component providing a vulcanizing site.

The basic production method of such a copolymer is disclosed inJP-A-58-71906 (U.S. Pat. No. 4,487,903).

Proportions of the perfluoroalkylene, the perfluoroalkyl vinyl ether ofthe formula (I) and the component providing a vulcanizing site are notlimited, and may be suitably selected according to the propertiesrequired for the perfluororubbers.

In general, 0.1 to 60% by mole of the perfluoroalkyl vinyl ether of theformula (I), 35 to 95% by mole of the perfluoroalkylene and 0.01 to 5%by mole of the component providing a vulcanizing site are polymerized.

When a peroxide vulcanizing system is used as a vulcanizing system,examples of the component providing a vulcanizing site include acompound of the formula (II):

RBr_(x)I_(y)  (II)

wherein R is a hydrocarbon group having 1 to 8 carbon atoms, afluorohydrocarbon group having 1 to 8 carbon atoms or achlorofluorohydrocarbon group having 1 to 8 carbon atoms, x is aninteger of 0 to 2, and y is an integer of 0 to 2, provided that the sumof x and y is at least 1, a compound of the formula (III):

CF₂═CF—O(CF₂CFYO)_(a)—(CF₂CF₂CH₂O)_(b)—CF₂CF₂CH₂Z  (III)

wherein Y is a fluorine atom or a trifluoromethyl group, Z is a hydrogenatom or a halogen atom, a is an integer of 0 to 2, and b is an integerof 0 to 5, a compound of the formula:

CX₂═CXO(CX₂)_(n)Y

wherein X is a hydrogen atom or a fluorine atom, Y is a bromine atom oran iodine atom, and n is an integer of 1 to 9, and4-bromo-3,3,4,4-tetrafluorobutene-1.

When a polyol vulcanizing system is used as a vulcanizing system,preferable examples of the compound providing a vulcanizing site includeperfluorophenoxy-substituted olefins.

When a triazine vulcanizing system is used as a vulcanizing system,preferable examples of the compound providing a vulcanizing site includecyano-substitute perfluoro(alkyl vinyl ethers) such as CF₂═CF—OCF₂CF₂CN,perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene), etc.

Other rubber may be selected according to the vulcanizing system whichis employed to vulcanize the perfluororubber.

Examples of the other rubber include peroxide-vulcanizable fluororubbersdisclosed in JP-A-53-125491 (U.S. Pat. No. 4,243,770);polyol-vulcanizable fluororubbers disclosed in JP-A-51-17969; rubbershaving crosslinkable sites disclosed in JP-A-55-108410 (U.S. Pat. No.4,530,972) and JP-A-62-12734 (U.S. Pat. No. 5,001,278); andcrosslinkable general-purpose rubber disclosed in JP-A-55-50050 (U.S.Pat. No. 4,251,399).

The polyfunctional compound used to form the adhesive layer may also beselected according to the vulcanizing system which is employed tovulcanize the perfluororubber.

In the case of the peroxide vulcanizing system, examples of thepolyfunctional compounds include polyfunctional vinyl compounds,polyfunctional allyl compounds, polyfunctional (meth)acrylic acidesters, etc. Preferable examples of such compounds include triallylcyanurate, triallyl isocyanurate, fluorinated triallyl isocyanurate,triacrylformal, triallyl trimellitate, ethylene-bismaleimide,N,N′-m-phenylene-bismaleimide, dipropargyl terephthalate, diallylphthalate, tetraallyl terephthalamide, tris(diallylamine)-s-triazine,triallyl phosphite, N,N-diallyl acrylamide, trimethylolpropanetrimethacrylate, etc.

In the case of the polyol vulcaning system, examples of thepolyfunctional compounds include polyhydroxy compounds,poly(pentafluorophenyl) compounds, etc. Preferable examples of suchcompounds include bisphenol A, bisphenol AF, hydroquinone, and theirpotassium salts, etc.

In the case of the triazine vulcanizing sytem, the polyfunctionalcompounds may be polycyano compounds.

Hereinafter, a vulcanizable composition of the perfluororubber and avulcanizable composition of the other rubber, which are preferably usedwith each of the above vulcanizing systems, will be explained.

(1) Peroxide Vulcanizing System

When the peroxide vulcanizing system is used as a vulcanizing system,the vulcanizable composition of the perfluororubber comprises theperfluororubber, an organic peroxide and a polyfunctional unsaturatedcompound.

A particularly preferable perfluororubber for the peroxide-vulcanizingcomposition is a copolymer of tetrafluoroethylene, the perfluoroalkylvinyl ether (I) and the above-described component providing avulcanizing site. Among others, a copolymer comprisingtetrafluoroethylene, a perfluoroalkyl vinyl ether of the formula (I) inwhich Rf is a perfluoromethyl group and n is 0, a component providing avulcanizing site of the formula (III) in which Z is an iodine atom and aand b are both 0, and a component providing a vulcanizing site of theformula (II) in which R is C₂F₄, x is 0 and y is 2; and a copolymercomprising tetrafluoroethylene, perfluoromethyl vinyl ether (aperfluoroalkyl vinyl ether of the formula (I) in which Rf is atrifluoromethyl group and n is 0), a component providing a vulcanizingsite of the formula (III) in which Z is an iodine atom and a and b areboth 0, and a component providing a vulcanizing site of the formula (II)in which R is C₂F₄, x is 0 and y is 2 are particularly preferable.

In general, an organic peroxide may be a compound which can readilygenerate a peroxide radical in the presence of heat or a redox system.Preferable examples of the organic peroxide include1,1-bis(tert.-butylperoxy)-3,5,5-trimethylcyclohexane,2,5-dimethylhexane-2,5-dihydroperoxide, di-tert.-butyl peroxide,tert.-butylcumyl peroxide, dicumyl peroxide,αα′-bis(tert.-butylperoxy)-p-diisopropylbenzene,2,5-dimethyl-2,5-di(tert.-butylperoxy)hexane,2,5-dimethyl-2,5-di(tert.-butylperoxy)hexyne-3, benzoyl peroxide,tert.-butylperoxybenzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane,tert.-butylperoxyisopropyl carbonate, etc. Among them, dialkyl typeperoxides are particularly preferable.

Examples of the polyfunctional compound to be contained in thevulcanizable composition are the same as those exemplified as thepolyfunctional compounds to be used in the adhesive layer.

When the peroxide vulcanizing system is used, the vulcanizablecomposition of the other rubber comprises the other rubber (e.g. afluororubber or a non-fluorinated rubber), an organic peroxide and apolyfunctional compound.

As the other rubbers, fluororubbers other than the perfluororubbers arepreferable. For example, vinylidene fluoride base fluororubberscontaining iodine and/or bromine atoms, tetrafluoroethylene basefluororubbers are preferable. Examples of the vinylidene fluoride basefluororubbers include vinylidene fluoride-hexafluoropropylenecopolymers, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylenecopolymers, etc. Examples of the tetrafluoroethylene base fluororubbersinclude tetrafluoroethylene-propylene copolymers. Examples of otherfluororubbers include hexafluoropropylene-ethylene copolymers.

The other rubber may be any rubber that can be vulcanized with anorganic peroxide. Apart from the above fluororubbers, silicone rubbers,fluorosilicone rubbers, EPDM, SBR, NBR, H-NBR, acrylic rubbers,epichlorohydrin rubbers and the like can be used.

The organic peroxide and the polyfunctional compound, which arecontained in the vulcanizable composition of the other rubber, may bethe same as those exemplified above.

Amounts of the rubber, organic peroxide and polyfunctional compound tobe contained in the vulcanizable composition of the perfluororubber orthe other rubber may be the same as those in the conventionalvulcanizable compositions. For example, 0.05 to 10 wt. parts, preferably0.5 to 5 wt. parts of the organic peroxide, and 0.1 to 20 wt. parts,preferably 0.5 to 10 wt. parts of the polyfunctional compound arecompounded in 100 wt. parts of the rubber.

(2) Polyol Vulcanizing System

When the polyol vulcanizing system is used as a vulcanizing system, avulcanizable composition comprises the perfluororubber and a polyhydroxycompound.

A preferable perfluororubber for the polyol-vulcanizing composition is acopolymer of tetrafluoroethylene, a perfluoroalkyl vinyl ether (I) andthe above-described component providing a vulcanizing site. Amongothers, a copolymer comprising tetrafluoroethylene, perfluoromethylvinyl ether and CF₂═CF—OCF₂CF(CF₃)O—C₆F₅ is particularly preferable.

The polyhydroxy compound may be any conventional polyhydroxy compound.Preferable examples of the polyhydroxy compound include bisphenol A,bisphenol AF, their potassium salts, etc.

When the polyol vulcanizing system is used, the vulcanizable compositionof the other rubber comprises the other rubber and the polyhydroxycompound. When the fluororubber is used, the composition may furthercontain an onium salt (e.g. quaternary ammonium salts or quaternaryphosphonium salts).

As the other rubbers, fluororubbers other than the perfluororubbers arepreferable. Examples of the fluororubbers include vinylidene fluoridebase fluororubbers such as vinylidene fluoride-hexafluoropropylenecopolymers and vinylidenefluoride-hexafluoropropylene-tetrafluoroethylene copolymers.

Apart from the above fluororubbers, epichlorohydrin rubbers may be usedas the other rubbers.

The polyhydroxy compound contained in the vulcanizable composition ofthe other rubber is the same as that exemplified above.

Amounts of the rubber, polyhydroxy compound and optional onium salt tobe contained in the vulcanizable composition of the perfluororubber orthe other rubber may be the same as those in the conventionalvulcanizable compositions. For example, 0.1 to 20 wt. parts of thepolyhydroxy compound and 0 to 5 wt. parts of the onium salt arecompounded in 100 wt. parts of the rubber. If desired, an acid acceptorsuch as magnesium oxide, calcium hydroxide, etc. may be used.

(3) Triazine Vulcanizable Composition

When the triazine vulcanizing system is used as a vulcanizing system,the vulcanizable composition comprises the perfluororubber and anorganic tin compound.

A preferable perfluororubber for the triazine-vulcanizing composition isa copolymer of tetrafluoroethylene, a perfluoroalkyl vinyl ether (I) andthe above-described component providing a vulcanizing site. Amongothers, a copolymer comprising tetrafluoroethylene, perfluoromethylvinyl ether and CF₂═CF—OCF₂CF(CF₃)O—CF₂CF(CF₃)CN is particularlypreferable.

The organic tin compound may be any conventional organic tin compound.Preferable examples of the organic tin compound include triphenyltin,trioctyltin, dibutyltin dilaurate, etc.

When the triazine vulcanizing system is used, the vulcanizablecomposition of the other rubber comprises the other rubber and theorganic tin compound.

As the other rubbers, fluororubbers other than the perfluororubbers arepreferable. Examples of the fluororubbers include vinylidene fluoridebase fluororubbers such as vinylidene fluoride-hexafluoropropylenecopolymers and vinylidenefluoride-hexafluoropropylene-tetrafluoroethylene copolymers. A componentproviding a vulcanizing site may be CF₂═CF—OCF₂CF(CF₃)O—CF₂CF(CF₃)CN.

Amounts of the rubber and organic tin compound to be contained in thevulcanizable composition of the perfluororubber or the other rubber maybe the same as those in the conventional vulcanizable compositions. Forexample, 0.1 to 20 wt. parts of the organic tin compound is compoundedin 100 wt. parts of the rubber.

Any of the above vulcanizable rubber compositions may containconventional fillers, reinforcing agents, pigments, processing aids,stabilizers, etc.

Examples of the inorganic fillers, reinforcing agents and pigmentsinclude carbon black, titanium oxide, silicon dioxide, talc, clay,calcium carbonate, diatomaceous earth, bariumsulfate, zinc oxide, etc.,and examples of the organic fillers, reinforcing agents and pigmentsinclude fluorine-containing polymers such as polytetrafluoroethylene,polyvinylidene fluoride, polychlorotrifluoroethylene,tetrafluoroethylene-ethylene copolymers, tetrafluoroethylene-vinylidenefluoride copolymers, etc.

The mixing of the composition may be carried out with any conventionalmeans. For example, open rolls, internal kneaders, and the like areused.

The laminates of the present invention can be used in variousapplications, for example, oil-, chemical- or weather-resistantpackings, O-rings, hoses, other sealing members, diaphragms and valvesfor use in transportations such as automobiles, ships, aircraft, etc.;packings, O-rings, sealing members, diaphragms, valves, hoses, rolls andtubes used in chemical plants; packings, O-rings, hoses, sealingmembers, belts, diaphragms, valves, rolls and tubes used in food plantequipment or food processing equipment (including domestic equipment);packings, O-rings, hoses, sealing members, diaphragms, valves and tubesused in nuclear power plant equipment; packings, O-rings, hoses, sealingmembers, diaphragms, valves, rolls, tubes, mandrels, electric wires,flexible joints, belts, rubber plates, weather strips used in generalindustrial parts, roll blades of PPC copying machines; and the like.

More specifically, the laminates of the present invention can be used inthe following applications:

A. Automobile industries

1) Sealing purpose

Core valves for needle valves of carburetors

Flange gaskets of carburetors

Power piston packings

O-ring for fuel-mixing pumps of automobiles

Seals of cylinder liners

Seals of valve stems

Front pump seals of automatic transmissions

Real axle pinion seals

Gaskets of universal joints

Pinion seals of speedometers

Piston cups of foot brakes

O-rings and oil seals for torque transmission

Seals for afterburning apparatuses of exhaust gas

Bearing seals

O-rings of fuel pumps

Seals of fuel hoses

Seals for automobile air conditioners

2) Hoses

Fuel hoses

EGR (exhaust gas recirculation) tubes

Twin carburetor hoses

3) Diaphragms

Diaphragms of fuel pumps

Diaphragms for sensors of carburetors

4) Others

Vibration-proof rubbers (e.g. motor mounts, exhaust systems)

B. Chemical industries

1) Seals

Seals of pumps, flow meters and pipes for chemicals

Seals of heat exchangers

Packings of glass condensers of sulfuric acid-producing apparatuses

Seals of pumps for diffusing and transferring agrochemicals

Seals of gas pipes

Seals for plating liquids

Packings of high temperature vacuum driers

Roller seals of paper-making belts

Seals of fuel batteries

Joint seals of wind tunnels

2) Rolls

Triclene(trichloroethylene)-resistant rolls (for dyeing fibers)

3) Others

Acid-resistant hoses (for conc. sulfuric acid)

packings for tube joints of gaschromatographic apparatuses and pH meters

Hoses for transferring chlorine gas

Rainwater-draining hoses for tanks of benzene or toluene

Seals, tubes, diaphragms and valve parts of analytical apparatuses andscientific apparatuses

C. General instruments and machines

1) Seals

Seals of hydraulic and lubrication machines

Bearing seals

Seals of dry copying machines

Seals for windows of dry-cleaning machines

Seals of enriching apparatuses for uranium hexafluoride

Seal (vacuum) valves of cyclotrons

Seals of automatic packaging machines

2) Others

Printing rolls, scrapers, tubes and valve parts of printing facilities

Coating rolls, scrapers, tubes and valve parts of coating and paintingfacilities

Ink tubes, rolls and belts of printers

Belts and rolls of dry copying machines

Diaphragms of pumps for analyzing sulfite and chlorine gas in an air(pollution monitoring equipment)

Rolls and belts of printing presses

Squeezing rolls for pickling

D. Aircraft

Valve stem seals of jet engines

Hoses, gaskets and O-rings for fuel supply

Rotating shaft seals

Gaskets of hydraulic machines

Fire wall seals

E. Ships

Stern seals for propeller shafts of screws

Intake and exhaust valve stem seals of diesel engines

Valve seals of butterfly valves

Pivot seals of butterfly valves

F. Foods and medicines

Seals of plate type heat exchangers

Solenoid valves of vending machines

Vial stoppers

G. Appliances

Insulation oil caps for railways

Venting seals of liquid-tight type transformers

Jackets of oil well cables

Furthermore, the laminates of the present invention can be used asO-rings, sealing members, hoses, tubes, diaphragms, rolls, linings andcoatings installed at sites which require plasma-resistance in CVDapparatuses, etching apparatuses, oxidative diffusion apparatuses,sputtering apparatuses, ashing apparatuses, ion-implantation apparatusesassembled in facilities for the production of semiconductors, liquidcrystal panels, plasma display panels, plasma-addressing liquid crystalpanels, field emission display panels, solar battery substrates, etc.;O-rings, sealing members, hoses, tubes, diaphragms and rolls at siteswhich require chemical resistance in wet etchers, cleaning apparatuses,pipes for chemical liquid, pipes for gases, etc.; and O-rings, sealingmembers, hoses, tubes, diaphragms and rolls at sites which should bedust-free and metal-free in those apparatuses.

Specific examples of the sites requiring the plasma resistance includeO-rings and sealing members for gate valves, quartz windows, chambers,chamber lid, gates, bell jars, couplings, pumps, gas-controllingequipment, and the like, in the facilities for the production ofsemiconductors, liquid crystal panels, plasma display panels, etc.

Specific examples of the sites requiring the chemical resistance includeO-rings, sealing members, hoses, tubes, diaphragms of pumps, rolls forconveying wafers, and the like for resist-development liquids,resist-peeling liquids and wafer-cleaning liquids used in the facilitiesfor producing semiconductors, liquid crystal panels, plasma displaypanels, etc.

The specific lamination structures of the laminates of the presentinvention will be explained.

In the case of an O-ring or a square ring (having a square crosssection), as shown in FIG. 1, the core is made of other rubber 1, andthe perfluororubber 2 is laminated to surround the entire surface of thecore. Thereby, an O-ring or a square ring is provided, which hasdurability in an atmosphere in which it is in contact with a liquid thatcorrodes conventional rubbers.

Furthermore, only a part of an O-ring or a square ring, which partrequires a perfluororubbers, for example, a part in contact with acorrosive liquid, can be made of a layer of a perfluororubber. Forexample, as shown in FIGS. 2 to 7, only the radially inner or outersurface is formed with the layer of the perfluororubber 2, while otherpart is formed of the layer of the other rubber 1.

In the case of a rubber roll, the other rubber is wrapped around a metalcore, and the perfluororubber is further wrapped around the other rubberlayer to form a rubber roll.

When a hose or a tube has a double-layer structure, either one of theinner layer or the outer layer is made of the layer of theperfluororubber, while the other layer is made of the layer of the otherrubber. In the case of three or more layer structures, at least onelayer is made of perfluororubber, and the remaining layers are made ofthe other rubber. For example, in the case of the hose or tube havingthe three-layer structure, the innermost and outermost layers, which arein contact with a liquid flowing in the hose or tube, and an exterioratmosphere, respectively, are made of the perfluororubber, while theintermediate layer is made of the other rubber.

To reinforce the hose or tube, a braided yarn is provided between anypair of the layers.

In the case of a sheet-form article such as a diaphragm, when it has thetwo-layer structure, one layer is made of the perfluororubber, while theother layer is made of the other rubber. When the sheet-form article hasthe three or more layer structure, at least one layer is made of theperfluororubber, while the remaining layers are made of the otherrubber. For example, in the case of the three-layer structure, the twoouter layers are made of the perfluororubber, while the intermediatelayer is made of the other rubber.

In the case of a diaphragm, a reinforcing material such as a cloth maybe inserted between a pair of the layers, or embedded in each rubberlayer.

In the case of a vial stopper, a part of the stopper, which will be incontact with chemicals, is preferably made of the perfluororubber layer.

The laminate of the present invention may be produced by variousmethods.

For example, the polyfunctional compound is coated on the surface of atleast one of the perfluororubber layer or the other rubber layer,preferably on the surface of the other rubber layer, and both layers arelaminated with the coated surface facing the other layer, followed byvulcanizing the layers to bond them.

The polyfunctional compound may be used in the form of a dispersion or asolution. A dispersion medium or a solvent can be selected according tothe kind of the polyfunctional compound. Preferable examples of thesolvent include lower ketones and esters (e.g. acetone, methyl ethylketone, ethyl acetate, etc.), alcohols (e.g. methanol, etc.), andaromatic compounds (e.g. toluene, xylene, etc.)

The coating method may be dipping, brush coating, spray coating, and soon.

Before laminating the two layers, either the perfluororubber layer orthe other rubber layer is preferably primarily vulcanized to improve thedimensional accuracy of the finished laminate or the moldingprocessability.

After lamination, the layers are vulcanized to bond them.

The vulcanizing conditions depend on the kinds of the perfluororubberand the other rubber, the used vulcanizing system and vulcanizing agent,the kind of the molded article, etc. In general, the primaryvulcanization is carried out at a temperature of 100 to 230° C. for 1 to60 minutes, and the secondary vulcanization is carried out at atemperature of 100 to 300° C. for 0 to 48 hours.

EXAMPLES

Hereinafter, the present invention will be explained in detail by thefollowing Examples and Comparative Examples.

In the Examples and Comparative Examples, the properties of thelaminates are measured by the following methods:

Adhesion Strength Measurement

A rubber laminate sample for the measurement of adhesion strength, whichwas produced in the following examples, was subjected to the 180 degreepeel test using a tensile tester. Tensile tester: RTA-1T manufactured byORIENTEC KABUSHIKIKAISHA Pulling speed: 50 mm/min.

Solvent Resistance Test

A rubber laminate sample for the measurement of solvent resistance,which was produced in the following examples, was dipped in varioussolvents, and the percentage of the volume increase and the change ofhardness were measured.

Example 1

A composition consisting of 100 wt. parts of a fluorine-containingelastomer of a vinylidenefluoride-hexafluoropropylene-tetrafluoroethylene copolymer (50/30/20mole %) containing 0.2 wt. % of iodine (Mooney viscosity of 70 at 100°C.), 20 wt. parts of MT carbon, 4 wt. parts of triallyl isocyanurate(TAIC) (manufactured by NIPPON KASEI KABUSHIKIKAISHA), and 1.5 wt. partsof PERHEXA 25B (manufactured by NOF Corporation) was molded in the formof a sheet having sizes of 25 mm×50 mm×1 mm.

Then, a 10 wt. % solution of TAIC in methyl ethyl ketone was brushcoated on the surface of the above uncured rubber sheet to form anadhesive layer.

A composition consisting of 100 wt. parts of a perfluoroelastomer of atetrafluoroethylene-perfluoromethyl vinyl ether copolymer (60/40 mole %)containing 0.4 wt. % of iodine (Mooney viscosity of 50 at 100° C.), 20wt. parts of MT carbon (carbon black manufactured by CANCARB), 4 wt.parts of TAIC, and 1.5 wt. parts of PERHEXA 25B was molded in the formof a sheet having sizes of 25 mm×50 mm×1 mm, and then laminated on theuncured rubber sheet having the adhesive sheet. The laminate wasprimarily vulcanized at 150° C. for 10 minutes, and then secondarilyvulcanized at 180° C. for 4 hours to obtain a sample for the measurementof adhesion strength.

Separately, a composition consisting of 100 wt. parts of the abovefluorine-containing elastomer, 20 wt. parts of MT carbon, 4 wt. parts ofTAIC and 1.5 wt. parts of PERHEXA 25B was molded in the form of a solidcylinder having a diameter of 11 mm and a height of 4.5 mm as an innerlayer of the unvulcanized rubber.

Next, a 10 wt. % solution of TAIC in methyl ethyl ketone was brushcoated on the surface of the inner layer of the uncured rubber, anddried to form an adhesive layer.

A composition consisting of 100 wt. parts of the above perfluororubber,20 wt. parts of MT carbon, 4 wt. parts of TAIC and 1.5 wt. parts ofPERHEXA 25B was coated on the uncured rubber having the adhesive layerto form an outer layer of the uncured rubber.

Then, the obtained laminate was primarily vulcanized at 150° C. for 10minutes and secondarily vulcanized at 180° C. for 4 hours to obtain asample (a cylinder having a diameter of 13 mm and a height of 6.5 mm)for the measurement of solvent resistance.

Comparative Example 1

A sample of the measurement of adhesion strength and one for themeasurement of solvent resistance were produced in the same manners asthose in Example 1 except that an adhesive layer was formed from a 10wt. % solution of butyl acrylate in methyl ethyl ketone.

Comparative Example 2

Test samples were produced in the same manners as those in Example 1except that no adhesive layer was formed.

Comparative Example 3

Test samples were produced in the same manners as those in Example 1except that neither an adhesive layer nor an outer layer was formed.

Example 2

Test samples were produced in the same manners as those in Example 1except that a silicone rubber composition KE-7611-U (manufactured byShin-Etsu Chemical Co., Ltd.) was used in place of thefluorine-containing elastomer composition.

Comparative Example 4

Test samples were produced in the same manners as those in Example 2except that an adhesive layer was formed from a 10 wt. % solution ofbutyl acrylate in methyl ethyl ketone.

Comparative Example 5

Test samples were produced in the same manners as those in Example 2except that no adhesive layer was formed.

Comparative Example 6

Test samples were produced in the same manners as those in Example 2except that neither an adhesive layer nor an outer layer was formed.

Example 3

Test samples were produced in the same manner as those in Example 1except that, in place of the fluorine-containing elastomer composition,a composition consisting of 100 wt. parts of ZETBALL 2010 (hydrogenatedNBR manufactured by Nippon Zeon Co., Ltd.), 40 wt. parts of MAF-C(manufactured by TOKAI CARBON CO., LTD.), 2.8 wt. parts of PERHEXA 25B,1.0 wt. part of TAIC, 0.5 wt. part of stearic acid (manufactured by NOFCorporation), 1.5 wt. parts of NAUGURD 445 (manufactured by UNIROYALCHEMICAL), 1.5 wt. parts of NOKLACK MB (manufactured by OHUCHI SHINKOCHEMICAL INDUSTRIES, LTD.) and 5.0 wt. parts of zinc oxide (manufacturedby Sakai Chemical Industry Co., Ltd.) was used.

Comparative Example 7

Test samples were produced in the same manners as those in Example 3except that an adhesive layer was formed from a 10 wt. % solution ofbutyl acrylate in methyl ethyl ketone.

Comparative Example 8

Test samples were produced in the same manners as those in Example 3except that no adhesive layer was formed.

Comparative Example 9

Test samples were produced in the same manners as those in Example 3except that neither an adhesive layer nor an outer layer was formed.

The test samples produced in the Examples and Comparative Examples weresubjected to the above tests for measuring the properties. The resultsare shown in Table 1.

TABLE 1 Ex. 1 C. Ex. 1 C. Ex. 2 C. Ex. 3 Inner layer Fluorine-containingelastomer Adhesive layer TAIC Butyl None None acrylate Outer layerPerfluoroelastomer None Adhesion test 1 (After primary vulcanization)None Adhesion strength 2.7 2.1 NG (kgf/cm) (sticky) Failure stateCohesive Cohesive Interface failure failure failure Adhesion test 2(After secondary vulcanization) Adhesion strength 2.6 2.0 NG (kgf/cm)(sticky) Failure state Cohesive Cohesive Interface failure failurefailure Solvent resistance (in acetone at 24° C. for 17 days) testVolume increase (%) 12 12 12 195 Change of hardness −2 −2 −2 −38 (JIS A)Ex. 2 C. Ex. 4 C. Ex. 5 C. Ex. 6 Inner layer Silicone rubber Adhesivelayer TAIC Butyl None None acrylate Outer layer Perfluoroelastomer NoneAdhesion test 1 (After primary vulcanization) None Adhesion strength 2.51.5 NG (kgf/cm) (sticky) Failure state Cohesive Cohesive Interfacefailure failure failure Adhesion test 2 (After secondary vulcanization)Adhesion strength 2.5 1.5 NG (kgf/cm) (sticky) Failure state CohesiveCohesive Interface failure failure failure Solvent resistance (intoluene at 24° C. for 17 days) test Volume increase (%) 30 31 31 243Change of hardness −4 −5 −5 −32 (JIS A) Ex. 3 C. Ex. 7 C. Ex. 8 C. Ex. 9Inner layer Hydrogenated NBR Adhesive layer TAIC Butyl None Noneacrylate Outer layer Perfluoroelastomer None Adhesion test 1 (Afterprimary vulcanization) None Adhesion strength 2.9 1.8 NG (kgf/cm)(sticky) Failure state Cohesive Cohesive Interface failure failurefailure Adhesion test 2 (After secondary vulcanization) Adhesionstrength 2.8 1.6 NG (kgf/cm) (sticky) Failure state Cohesive CohesiveInterface failure failure failure Solvent resistance (in toluene at 24°C. for 17 days) test Volume increase (%)  4  5  5 121 Change of hardness−1 −2 −2 −27 (JIS A)

What is claimed is:
 1. A laminate comprising a first layer of aperfluororubber, wherein said perfluororubber is a copolymer of aperfluoroalkylene having 2 to 6 carbon atoms, a component providing avulcanizing site, and a perfluoroalkyl vinyl ether of the formula (I):Rf—O—(CFXCF₂O)_(n)—CF═CF₂  (I) wherein Rf is a perfluoroalkyl grouphaving 1 to 5 carbon atoms, X is a fluorine atom or a trifluoromethylgroup, and n is an integer of 0 to 4; a second layer of rubber otherthan a perfluororubber, and an adhesive third layer, disposed betweenthe first and second layers, containing a polyfunctional compound whichadheres the first and second layers by vulcanization; wherein saidpolyfunctional compound has a functional group which functions as avulcanizing site for said perfluororubber and a another group whichfunctions as a vulcanizing site for said rubber other than aperfluororubber; wherein said component providing a vulcanizing site isat least one component selected from the group consisting of4-bromo-3,3,4,4-tetrafluorobutene-1, a compound represented by formula(II), a compound represented by formula (III) and a compound representedby formula (IV); wherein said compounds of formulae (II), (III) and (IV)are as follows: a compound of formula (II): RBr_(x)I_(y)  (II) wherein Ris a hydrocarbon group having 1 to 8 carbon atoms, a fluorohydrocarbongroup having 1 to 8 carbon atoms or a chlorofluorohydrocarbon grouphaving 1 to 8 carbon atoms, x is an integer of 0 to 2, and y is aninteger of 0 to 2, provided that the sum of x and y is at least 1; acompound of the formula (III):CF₂═CF—O(CF₂CFYO)_(a)—(CF₂CF₂CH₂O)_(b)—CF₂CF₂CH₂Z  (III) wherein Y is afluorine atom or a trifluoromethyl group, Z is a hydrogen atom or ahalogen atom, a is an integer of 0 to 2, and b is an integer of 0 to 5;and a compound of formula (IV): CX₂═CXO(CX₂)_(n)Y  (IV) wherein X is ahydrogen atom or a fluorine atom, Y is a bromine atom or an iodine atom,and n is an integer of 1 to
 9. 2. The laminate according to claim 1,wherein said rubber other than a perfluororubber is afluorine-containing rubber other than a perfluororubber.
 3. The laminateaccording to claim 1 or 2, wherein said perfluororubber and said rubberother than a perfluororubber are vulcanized with the same polyfunctionalcompound as that contained in said adhesive layer.
 4. The laminateaccording to claim 1 or 2, which is in the form of an O-ring, a squarering, a rubber roll, a diaphragm, a rubber hose, a rubber tube or a vialstopper.
 5. The laminate according to claim 1, wherein saidperfluoroalkylene is tetrafluoroethylene.
 6. The laminate according toclaim 1, wherein 35 to 95% by mole of said perflubroalkylene, 0.01 to 5%by mole of said component providing a vulcanizing site, and 0.1 to 60%by mole of said perfluoroalkyl vinyl ether are polymerized.
 7. Thelaminate according to claim 1, wherein said component providing avulcanizing site is the compound of formula (II), wherein x is 0 and yis
 2. 8. A method for producing a laminate comprising a layer ofperfluororubber and a layer of rubber other than said perfluororubberlayer, said method comprising the steps of: coating a polyfunctionalcompound on a surface of at least one of said layer of theperfluororubber and said layer of the other rubber, laminating thelayers with the coated surface facing the other layer, and vulcanizingthe layers to adhere them; wherein said perfluororubber is a copolymerof a perfluoroalkylene having 2 to 6 carbon atoms, a component providinga vulcanizing site, and a perfluoroalkyl vinyl ether of the formula (I):Rf—O—(CFXCF₂O)_(n)—CF═CF₂  (I) wherein Rf is a perfluoroalkyl grouphaving 1 to 5 carbon atoms, X is a fluorine atom or a trifluoromethylgroup, and n is an integer of 0 to 4; and said component providing avulcanizing site is selected from the group consisting of4-bromo-3,3,4,4-tetrafluorobutene-1, a compound represented by formula(II), a compound represented by formula (III) and a compound representedby formula (IV); wherein said compounds of formulae (II), (III) and (IV)are as follows: a compound of formula (II): RBr_(x)I_(y)  (II) wherein Ris a hydrocarbon group having 1 to 8 carbon atoms, a fluorohydrocarbongroup having 1 to 8 carbon atoms or a chlorofluorohydrocarbon grouphaving 1 to 8 carbon atoms, x is an integer of 0 to 2, and y is aninteger of 0 to 2, provided that the sum of x and y is at least 1; acompound of the formula (III):CF₂═CF—O(CF₂CFYO)_(a)—(CF₂CF₂CH₂O)_(b)—CF₂CF₂CH₂Z  (III) wherein Y is afluorine atom or a trifluoromethyl group, Z is a hydrogen atom or ahalogen atom, a is an integer of 0 to 2, and b is an integer of 0 to 5;and a compound of formula (IV): CX₂═CXO(CX₂)_(n)Y  (IV) wherein X is ahydrogen atom or a fluorine atom, Y is a bromine atom or an iodine atom,and n is an integer of 1 to
 9. 9. The method according to claim 8,wherein either one of said layer of the perfluororubber and said layerof rubber other than said perfluororubber layer is primarily vulcanized,while the other layer is unvulcanized.
 10. The method according to claim8, wherein said polyfunctional compound is coated in the form of adispersion or a solution.
 11. The method according to claim 8, whereinsaid perfluoroalkylene is tetrafluoroethylene.